The avermectin series of compounds (formerly referred to as C-076 compounds) are derived from the natural products disclosed in U.S. Pat. No. 4,310,519 to Albers-Schonberg et. al. and the milbemycin series of compounds as derived from the natural products disclosed in U.S. Pat. No. 3,950,360 to Aoki et. al. The aglycone derivatives of the avermectin compounds are disclosed in U.S. Pat. No. 4,206,205 to Mrozik et. al. Other aglycone compounds with modified C-25 substituents are disclosed in EP 277916 (microbiologically produced) and UK 2167751 (synthetically produced). Avermectin compounds with a variety of 25-position substituents are disclosed in EPO 214731 and such compounds can be readily converted into the corresponding aglycones, which are starting materials for the instant process, following the procedures of U.S. Pat. No. 4,206,205 to Mrozik et al. Synthetic procedures are available for the glycosylation of avermectin compounds which are disclosed in U.S. Pat. No. 4,156,720 to Fisher et. al. and U.S. Pat. No. 4,205,967 to Fisher et. al. Such glycosylation procedures are generally non-selective and require the extensive use of protecting groups to ensure glycosylation at the desired position. The instant process is a selective procedure for the production of 13-mono-and di-glycosylated derivatives of avermectin aglycone compounds.